Author(s): Lin Hwei Chen, Davidson Hamer

The risk for illness or injury increases with duration of travel, so travelers planning long-term (commonly considered ≥6 months) visits to low- or middle-income countries require special consideration regardless of whether they are expatriates with definite plans or adventurers with open itineraries. Points to discuss in the pretravel consultation include accessing routine and emergency care at the destination, vaccines, infectious diseases not prevented by vaccines, injury prevention, and cultural and mental health issues that long-term travelers might encounter.

Accessing Care Abroad

Before departure, all long-term travelers should undergo complete medical and dental examinations. For expatriates, a mental health evaluation prior to travel could identify and help address underlying issues that often cause early repatriation. Travelers should anticipate that they will need care at some point during their stay and plan where they will obtain it and how they will pay for it.

People traveling for work or with an organization (e.g., a nongovernmental organization, Peace Corps, a university) might have a predetermined source for care; some might access advice from the international expatriate community. By contrast, other travelers should identify a health care source in advance (see Sec. 6, Ch. 2, Obtaining Health Care Abroad). Long-term travelers also should determine whether they will need supplemental travel health insurance and evacuation insurance (see Sec. 6, Ch. 1, Travel Insurance, Travel Health Insurance & Medical Evacuation Insurance).

In some countries, travelers are likely to encounter medications of poor quality that are substandard, falsified, counterfeit, or expired. Because the pills and packaging could be nearly indistinguishable from their legitimate counterparts, travelers should bring a sufficient supply of their routine medications (e.g., antihypertensive or antihyperlipidemic drugs) from the United States (see Sec. 6, Ch. 3, . . . perspectives: Avoiding Poorly Regulated Medicines & Medical Products During Travel).

Controlled substances and certain over-the-counter and commonly prescribed medications are illegal to bring into some countries. The International Society of Travel Medicine Pharmacist Professional Group offers the Database on International Regulations on Importation of Medicines for Personal Use (Table 9-02). The International Narcotic Control Board website includes guidelines provided by each country and is a good reference for travelers looking for information about whether they can legally import their medications to their destinations (Table 9-02).

Options for obtaining sufficient medications include requesting an override from the insurance company to dispense the entire quantity of medication; paying out-of-pocket for the full amount of medication needed and then submitting to the insurance company for reimbursement; refilling prescriptions during trips home; or relying on visiting friends or family members to bring refilled medication supplies.

Vaccines

Long-term travelers should be aware of any vaccine requirements for entry, employment, or schooling at their destination. Update routine vaccines, including influenza vaccine, before travelers depart, and consider disease risk in surrounding areas because long-term travelers are likely to travel locally. A short-term traveler to Seoul, for example, would not be considered at risk for Japanese encephalitis (JE), but expatriates living in Seoul might have opportunities to visit the Korean countryside or other areas in Asia where they could be exposed to the JE virus. Similarly, consider yellow fever vaccination even if the posting location is not in an endemic area, because the traveler might journey to endemic areas while living abroad.

Hepatitis A & Typhoid Fever

Given the cumulative risk for hepatitis A and typhoid fever infection among long-term travelers, vaccination against these two diseases is appropriate (see Sec. 5, Part 2, Ch. 7, Hepatitis A, and Sec. 5, Part 1, Ch. 24, Typhoid & Paratyphoid Fever). Neither of the US Food and Drug Administration (FDA)–approved typhoid vaccines, however, effectively prevents infection in all recipients; the injectable (ViCPS) and the oral (Ty21a) vaccine are each estimated to protect ≈50%–80% of recipients from infection. Thus, travelers who receive these vaccines should still adhere to safe food and water precautions (see Sec. 2, Ch. 8, Food & Water Precautions). Moreover, duration of protection afforded by each vaccine is limited; a repeat dose of ViCPS is recommended every 2 years for travelers at continued risk of infection. For Ty21a recipients, a booster is recommended every 5 years.

Hepatitis B

Travel-associated hepatitis B infections are rare, but the risk for travelers might be greater than for nontravelers, especially for long-term travelers and expatriates, so consider hepatitis B vaccine for this population (see Sec. 5, Part 2, Ch. 8, Hepatitis B).

Japanese Encephalitis

Infection with JE virus is associated with longer stays in endemic areas. JE vaccine is recommended for travelers who plan longer stays or residence in endemic areas, travelers anticipating outdoor activities in endemic areas after dusk, and travelers who are uncertain of specific destinations or activities (see Sec. 5, Part 2, Ch. 13, Japanese Encephalitis).

Meningococcal

Meningococcal disease is more likely in travelers with prolonged exposure to local populations in endemic or epidemic areas; consider quadrivalent conjugate vaccine for at-risk travelers (see Sec. 5, Part 1, Ch. 13, Meningococcal Disease)

Rabies

Rabies preexposure prophylaxis is an important consideration for people spending prolonged time in endemic countries, especially in places where rabies immune globulin is not available, which is true of many low- and middle-income countries. Prioritize vaccination for children who will be living in high-risk areas (see Sec. 5, Part 2, Ch. 18, Rabies, and Sec. 5, Part 2, Ch. 19, . . . perspectives: Rabies Immunization).

Yellow Fever

Yellow fever vaccination might be required by some countries or recommended for endemic areas (see Sec. 2, Ch. 5, Yellow Fever Vaccine & Malaria Prevention Information, by Country, and Sec. 5, Part 2, Ch. 26, Yellow Fever). For instance, numerous unvaccinated Chinese expatriates became ill with yellow fever while working in Angola during the outbreak there in 2016, illustrating the importance of yellow fever vaccination for people who will be living or working in endemic areas.

Infectious Diseases Not Prevented By Vaccines

Dengue & Other Arboviral Diseases

Dengue seroconversion among long-term travelers from the Netherlands with median travel duration of 20 weeks found an attack rate of 6.5% or incidence rate of 13.9 per 1,000 person-months travel in endemic areas. Other mosquito-borne viral illnesses (e.g., chikungunya, Zika), also pose potential risk. Advise long-term travelers and expatriates to protect themselves from mosquito vectors (see Sec. 4, Ch. 6, Mosquitoes, Ticks & Other Arthropods); most travelers are not candidates to receive dengue vaccine (for details, see Sec. 5, Part 2, Ch. 4, Dengue). Section 5 also provides disease-specific information on chikungunya and Zika virus infections.

Hepatitis C & Hepatitis E

Transfusion is a potential source of hepatitis C virus infection in expatriates. Hepatitis E virus is spread by the fecal–oral route; the risk for infection is greatest in Asia, although it has been transmitted in many different tropical locations. Pregnant people are at greatest risk for fulminant disease from hepatitis E. For more information on these infections, see the relevant chapters in Section 5.

HIV & Sexually Transmitted Infections

Travelers and expatriates are at increased risk for HIV and sexually transmitted infections (STIs), and the consistency of condom use among expatriates is low (see Sec. 9, Ch. 12, Sex & Travel). Educate long-term travelers about the risk for HIV and STIs at their destination, as well as preventive measures. Consider the potential for occupational exposure to HIV among health care workers, and during the pretravel consultation include discussions of postexposure prophylaxis with antiretroviral therapy and risk avoidance (see Sec. 5, Part 2, Ch. 11, Human Immunodeficiency Virus / HIV, and Sec. 9, Ch. 4, Health Care Workers, Including Public Health Researchers & Medical Laboratorians).

Malaria

For long-term travelers, emphasize the importance of adjuncts to prophylaxis (see Sec. 4, Ch. 6, Mosquitoes, Ticks & Other Arthropods)). Even when urged to adhere to personal protective measures and reassured that long-term prophylaxis is safe and effective, traveler adherence likely will decline over time. Consequently, the pretravel consultation for a long-term traveler to malaria-endemic areas should stress the severity of the disease, its signs and symptoms, and the need to seek care immediately if signs and symptoms develop. Travelers also can consider bringing a reliable supply of drugs to treat malaria (atovaquone-proguanil or artemether lumefantrine) if they are diagnosed with the disease (see Sec. 2, Ch. 5, Yellow Fever Vaccine & Malaria Prevention Information, by Country, and Sec. 5, Part 3, Ch. 16, Malaria).

Risk Factors Contributing to Infection

Data suggest that malaria incidence increases, and use of preventive measures decreases, with increasing length of stay abroad. Among expatriate corporate employees in Ghana, adherence to malaria prophylaxis deteriorated with increasing duration of stay, and all employees who had been on the site for >1 year had abandoned prophylaxis. About half of the cohort only intermittently used insect repellent, and more than one-third never used repellent.

Even though most British expatriates from the UK Foreign and Commonwealth Office had good knowledge about malaria and its prevention strategies, they adhered to malaria prophylaxis <25% of the time; only 25% reported rigorous compliance, and 13% reported having contracted malaria. A recent GeoSentinel Global Surveillance Network analysis found that Plasmodium falciparum malaria was the most frequent diagnosis among ill returned expatriate workers, occurring in 6%, and was acquired most commonly in sub-Saharan Africa. Given the high risk for malaria among travelers in Africa, these data on long-term travelers and expatriates highlight worrisome risks and practices.

French service members deployed to the Central African Republic for 4 months in 2013 experienced malaria at a rate of 150 cases per 1,000 person-years. A survey found that prophylaxis compliance correlated positively with use of other prophylactic measures against malaria (e.g., insecticide-treated clothing, mosquito net use, taking prophylaxis at the same time every day), correct perception of malaria risk, favorable perception of prophylaxis effectiveness, and peer-to-peer reinforcement.

Chemoprophylaxis

A traveler residing in an area of continuous malaria transmission should continue to use malaria prophylaxis for the entire stay. Doxycycline has been well tolerated for long-term malaria prophylaxis in the military, and the Centers for Disease Control and Prevention (CDC) has no recommended limits on its duration of use for malaria prophylaxis. Peace Corps volunteers frequently use mefloquine during prolonged stays and have a discontinuation rate of 0.9%. Mefloquine might be appropriate for long-term prophylaxis in chloroquine-resistant areas because of its convenient weekly dosing, but concern has increased regarding its neuropsychiatric side-effect profile, especially because the FDA label indicates that neurologic side effects could persist.

Atovaquone-proguanil has shown good long-term tolerability in post-marketing surveillance, with a discontinuation rate of only 1% because of diarrhea; for long-term use, however, atovaquone-proguanil can be a more expensive option than other antimalarial drugs. Peace Corps volunteers prescribed atovaquone-proguanil adhered to prophylaxis better than did people given doxycycline and mefloquine. If extended (>5 years) use of chloroquine is planned, a baseline ophthalmic examination with biannual follow-up is recommended to screen for potential retinal toxicity.

Because of its convenient weekly dosing, the antimalarial drug tafenoquine appears to be a promising choice for long-term travelers; an association with vortex keratopathy might limit its use. Moreover, tafenoquine use should be avoided in people with documented glucose-6-phosphate-dehydrogenase (G6PD) deficiency, as well as in those who have not been tested for G6PD deficiency. It is also not recommended for use in people with a history of psychotic disorder. Pregnancy is a contraindication to tafenoquine use.

Pregnancy

The possibility of pregnancy requires careful consideration for travelers to areas where malaria is endemic (see Sec. 5, Part 3, Ch. 16, Malaria, and Sec. 7, Ch. 1, Pregnant Travelers). Malaria infection during pregnancy can result in severe complications to both mother and fetus. When pregnancy is anticipated, prophylaxis options might need to be adjusted; explore the possibility of pregnancy with all long-term travelers of childbearing age before departure.

For a person who is pregnant or who plans to become pregnant during long-term travel, mefloquine is considered safe in all trimesters. Data from published studies in pregnant people have shown no increase in the risk for teratogenic effects or adverse pregnancy outcomes after mefloquine prophylaxis during pregnancy. Chloroquine also has been used long-term without ill effects on pregnancy. If a person traveling long-term is taking atovaquone-proguanil, doxycycline, or primaquine, they should discontinue their medication and begin weekly mefloquine (or chloroquine in those areas where it remains efficacious) for at least 3–4 weeks to build up a therapeutic blood level of mefloquine before attempting to conceive.

During the pretravel consultation, advise people of the potential risks associated with becoming pregnant while taking antimalarial drugs. Doxycycline, for example, is associated with fetal toxicity in animal studies, and its use is contraindicated during pregnancy. Primaquine and tafenoquine can harm a G6PD-deficient fetus, so should not be used. The effect of atovaquone-proguanil on the fetus is unknown.

Other Parasitic Infections

Parasitic infections vary with location and include amebiasis, filariasis, giardiasis, cutaneous leishmaniasis, schistosomiasis, and strongyloidiasis; vectorborne infections (e.g., filariasis, cutaneous leishmaniasis) can be prevented by using insect bite precautions and protective clothing, and by avoiding locations where the vectors are prevalent (see Sec. 5, Part 3, Ch. 9, Lymphatic Filariasis, and Sec. 5, Part 3, Ch. 14, Cutaneous Leishmaniasis). For travelers with appropriate (or potential) geographic exposure risks, consider the possibility of filariasis and cutaneous leishmaniasis.

Travelers can avoid schistosomiasis by not bathing, swimming, or wading in fresh water, guidance that can be difficult to communicate to long-term travelers who, for example, might be living in sub-Saharan Africa and looking forward to river rafting or vacationing at a lake. Travelers can prevent Strongyloides stercoralis and hookworm infections by not walking barefoot through soil or on sandy beaches. The risks for schistosomiasis and strongyloidiasis can increase with long-term travel; consider screening travelers on their return, and suggest that people with access to health care also seek screening during long-term expatriate assignments (for details, see Sec. 11, Ch. 3, . . . perspectives: Screening Asymptomatic Returned Travelers). Although seropositivity appears to be generally low for many parasitic infections, seroconversion for Schistosoma spp. occurred in 6% of Dutch long-term travelers to endemic areas.

Avoiding unwashed or uncooked foods, including greens and vegetables, can help reduce a travelers’ chances of ingesting foodborne parasites (e.g., Ascaris).

Travelers’ Diarrhea

Because diarrhea and gastrointestinal diseases occur commonly, educate long-term travelers about ways to manage gastrointestinal illnesses (see Sec. 2, Ch. 6, Travelers’ Diarrhea), including rehydration, use of antimotility agents, empiric antimicrobial therapy, and knowing when to seek care.

Compared with short-term travelers, long-term travelers experience more chronic diarrhea and postinfectious irritable bowel syndrome, possibly because some become less adherent to food and water precautions over time. Advise travelers of the need to continue food and water precautions to reduce the risk for these conditions (see Sec. 2, Ch. 8, Food & Water Precautions).

Tuberculosis

In destinations where the burden of tuberculosis (TB) is high, the risk of infection in travelers can rise to that of the local population, depending on their length of stay and closeness of contact with the local population. For long-term travelers, consider a baseline interferon-γ release assay or a tuberculin skin test before travel, and repeat the same test after travel. TB screening is particularly important for health care workers or people working in hospitals, prisons, or refugee camps (see Sec. 5, Part 1, Ch. 23, . . . perspectives: Testing Travelers for Mycobacterium tuberculosis Infection).

Injury

Because injuries are the leading cause of preventable death in travelers, educate long-term travelers about safety. Stress the importance of road and vehicle safety, and emphasize that travelers should choose the safest vehicle options available (see Sec. 8, Ch. 5, Road & Traffic Safety). Roads are often poorly constructed and maintained, traffic laws might not be enforced, vehicles might not have seatbelts or be kept in good condition, and local drivers might be reckless and minimally trained. See Sec. 4, Ch. 12, Injury & Trauma, for strategies to reduce the risk of traffic and other injuries.

Mental Health

Culture shock and the stress of long-term travel can trigger or exacerbate mental illness. Assess long-term travelers for a preexisting diagnosis of mental illness, depressed mood, recent major life stressors, and use of medications that can adversely affect mental health. Any of these conditions suggest a need for further screening.

Warn all long-term travelers against illicit drug use, and urge them to take care of their physical and mental health by exercising regularly and eating healthfully. Travelers should be able to recognize signs of anxiety and depression and have a plan for coping. Having photographs or other mementos of friends and family at hand, and staying in close contact with loved ones at home, can alleviate the stress of long-term travel (see Sec. 2, Ch. 12, Mental Health).

Long-Term Travelers With Open Itineraries

Offering pretravel care to long-term travelers, especially travelers with no itinerary or who have only vague travel plans, presents unique challenges. These travelers benefit from broad immunization coverage for all potential exposures to vaccine-preventable diseases.

Because their plans are unclear, these travelers must understand that they might need to diagnose and treat themselves for common ailments, including musculoskeletal problems, upper respiratory tract infections, skin disorders, travelers’ diarrhea, urinary tract infections, and vaginitis. For travelers (e.g., backpackers) who might go in and out of malaria-endemic areas, a sensible approach is to provide a supply of atovaquone-proguanil with instructions on how to take it when they visit risk areas.

In addition to strategies to prevent health problems and injuries during their long sojourns, traveler education is imperative regarding health resources, signs and symptoms that require urgent medical evaluation, and medical evacuation.

Screening Long-Term Travelers & Expatriates After Return

After returning to their country of origin, long-term travelers (e.g., highly adventurous travelers, expatriate workers, Peace Corps volunteers) ideally should have a thorough medical interview to assess potential infectious exposures. A careful itinerary-specific history with detailed questioning about potential high-risk exposures including animal, food and water, and human contacts is the foundation of the posttravel evaluation.

Conduct a physical examination focused on specific signs and symptoms, and a selected array of tests. These tests include a complete blood count with differential, hepatic transaminases, stool ova and parasite examination, and serologic markers depending on types of exposure, but most importantly for schistosomiasis and strongyloidiasis. Serologic testing can detect subclinical infections and help identify instances where treatment would be advised (see Sec. 11, Ch. 3, . . . perspectives: Screening Asymptomatic Returned Travelers). The posttravel evaluation also provides an opportunity for preventive counseling for potential future travel.